JPH0424855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for heat treatment of semiconductor wafers.

[Prior Art] Etching is one of the manufacturing processes for semiconductor devices, but in order to perform this etching, it is necessary to form a photoresist film on the surface of a semiconductor wafer such as a silicon wafer, and then photoprocess this. . In forming this photoresist film, a photoresist liquefied using a solvent is applied as a photoresist film on a wafer, and then a photoresist is applied to improve the photosensitivity, phenomenon processing characteristics, or etching processing characteristics of this film. The membrane is heat-treated to perform so-called modification. This modification includes solvent removal, increased adhesion,
This also includes improved etching resistance.

Heat treatment equipment such as infrared baking equipment, hot air circulation baking equipment, dielectric heating baking equipment, etc., and vacuum baking equipment are used as means for performing this type of reforming, but the former is preferred in terms of productivity and automation. is advantageous.

[Problems to be Solved by the Invention] In conventional heat treatment, the baking action is performed with the photoresist film exposed in the processing equipment, so foreign matter (dust, etc.) present in the equipment may be deposited on the photoresist film. It has the disadvantage of being easy to adhere to. If such foreign matter adheres to the photoresist film, the light will be blocked by the foreign matter during the exposure process, and the photoresist film under the foreign matter will not be exposed. As a result, a desired semiconductor element pattern cannot be obtained on the wafer, and in particular, if foreign matter adheres to the wiring portion, the wafer may be cut.

Therefore, in the past, it was considered essential to conduct a visual inspection after the heat treatment process of the photoresist film, and in fact, a large number of defective products were discovered during this inspection, reducing the product yield and reducing the number of man-hours in the product process. This has become an obstacle to reduction.

For this reason, the inventors of the present invention investigated the cause of the generation (adhesion) of foreign matter and found that foreign matter was generated from the drive unit for transporting objects on which a film was formed inside the heat treatment equipment, and objects were transferred from outside the equipment into the equipment. It was found that most of the foreign matter was contained in the outside air that entered during transport.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat treatment method that can prevent foreign matter from adhering to a photoresist film formed on a semiconductor wafer and provide a high yield.

[Means for Solving the Problems] The structure of the present invention includes the steps of applying a liquefied film using a solvent to the surface of a semiconductor wafer, and heating the semiconductor wafer having the applied film. A device characterized by comprising the steps of transporting the semiconductor wafer into a processing chamber, maintaining the inside of the heating processing chamber in a downflow state of clean gas, and heating the semiconductor wafer surface while applying the downflow state of clean gas to the surface of the semiconductor wafer. It is.

According to the present invention having such a configuration, since the interior of the heat treatment chamber is maintained in a downflow state of clean gas, foreign matter stagnant in the heat treatment chamber (solvent vapor removed from the coating film, foreign matter brought into the chamber) is removed. , foreign matter generated indoors) can be prevented from re-adhering to the semiconductor wafer surface, and heat treatment with a good yield can be achieved.

[Example] FIGS. 1 and 2 show a front sectional view and a side sectional view of an infrared baking device applied to the method of the present invention.

In the figure, reference numeral 1 denotes the main body of the apparatus, inside which a partition wall 2 is erected at a position closer to the rear side to define a circulation chamber 3 on the rear side, which includes an inert gas source (not shown). A gas supply pipe 4 connected to the gas supply pipe 4 is open and continuous. Mesh plates 5 and 6 are disposed on the front side of the partition wall 2 at the top and bottom, respectively, and define a ventilation chamber 7, a baking chamber (processing chamber) 8, and an exhaust chamber 9 in order from the top.

The partition wall 2 has through holes 10 in its upper and lower parts.
11, and an air supply fan 12 and an exhaust fan 13 are installed inside, so that gas is circulated along the route of circulation chamber 3 → ventilation chamber 7 → bake chamber 8 → exhaust chamber 9 → circulation chamber 3 as shown by the arrow. ing. Said circulation chamber 8
A pre-filter 14 is disposed at the through hole 10 that communicates with the ventilation chamber 7, and a main filter 15 is disposed between the ventilation chamber 7 and the baking chamber 8.

On the other hand, in the lower part of the baking chamber 8, a conveying means 16 having a belt conveyor as a driving unit is disposed in both directions, and conveys the wafer 17 from left to right in FIG. A loader section 18 and an unloader section 19 are arranged on the left and right sides of the main body 1, and the loader section 1
The 8 wafers 17 are transferred to the transport means 16 through the loading port 20 of the main body side wall 1a, and the transport means 16
The upper wafer 17 is transferred to the unloader section through the outlet 21 of the main body side wall 1a. Furthermore, three infrared lamps 22 are provided in the upper part of the bake chamber 8 in parallel with the transport means 16, so that the wafers transported by the transport means 16 can be heated. 2
8 is a reflecting plate.

[Effects of the Invention] According to the above configuration, the inert gas supplied from the gas supply pipe 4 into the circulation chamber 8 passes through the prefilter 1
The air enters the ventilation chamber 7 through the air filter 4, is purified through the main filter 15, and flows into the baking chamber 8. In the baking chamber 8, the gas flow is directed downward by the action of the mesh plate 5, resulting in a so-called downflow. Here, the foreign matter generated by the drive section of the conveyance means 16 is carried by a flow and moved downward, passed through the mesh plate 6 to the exhaust chamber 9, and then passed back to the circulation chamber 3. This gas will be circulated again through the same route as described above, and will be cleaned by the pre-filter 14 and the main filter 15, respectively.
The air is passed through the baking chamber 8 to remove foreign matter inside the baking chamber 8.

On the other hand, the wafer 17 is supplied into the bake chamber 8 from the loader section 18 through the loading port 20, and is heated (baked) by the radiant heat of the infrared lamp 22 and the heat of the heated gas in the bake chamber while being conveyed by the conveying means 16. After the heat treatment, it is carried out from the carrying out port 22 to the unloader section 19. At this time, by adjusting the flow rate of the gas to maintain a positive pressure (relative to the outside air) inside the bake chamber 8, the outside air is forced into the inlet 20 and the outlet 20 when wafers are loaded and unloaded.
1 does not enter the baking chamber 8, and therefore foreign matter contained in the outside air does not enter. The pressure inside the baking chamber 8 can be adjusted by adjusting the flow rate of the gas supplied from the gas supply pipe 4, the rotational speed of the air supply fan 12, and the like.

As a result of the above, foreign matter generated from the drive unit of the conveying means is removed in the bake chamber 8, and foreign matter contained in the outside air is removed from the bake chamber 8 along with the outside air.
This prevents foreign matter from adhering to the photoresist film formed on the surface of the wafer 17, thereby improving product yield.

[Modifications] FIGS. 3 to 5 show other different embodiments of heating devices applied to the present invention. In these figures, the same parts as those in the embodiment described above are designated by the same reference numerals, and the explanation thereof will be omitted.

Figure 3 shows the configuration as a hot air circulation system.
In place of the infrared lamps 22 in the previous example, heaters 24 are arranged on both side walls of the circulation chamber 8 to heat the gas as it flows through the circulation chamber 8 and ventilate it to the baking chamber 8.
The wafer 17 is heated.
The gas supply pipe 4 is connected to the lower part of the circulation chamber 3.

FIG. 4 shows a plate heating system, in which a heater 25 is installed inside a belt conveyor serving as the conveying means 16, and the wafers conveyed thereon are heated from a close distance.

FIG. 5 shows a dielectric heating (microwave heating) system configuration in which a magnetron 26 is placed in the ventilation chamber 7 and microwaves are radiated into the baking chamber 8 to dielectrically heat the wafer 17. .

As mentioned above, although each example has a different heating method,
It is the same as the previous example in that the inert gas is thrown down into the baking chamber and the pressure inside the baking chamber is made positive, and it goes without saying that the adhesion of foreign matter can be prevented in the same way as in the previous example.

Here, the heating device applied to the present invention can be applied to other devices as long as it has a processing space and requires cleanliness between processing chambers, such as a photoresist pre-bake furnace, It can be applied to photoresist post-bake ovens, automatic coating and baking equipment, and automatic developing and baking equipment.

As described above, according to the present invention, the gas is caused to flow down into the processing chamber, and the pressure inside the processing chamber is particularly positive, so that foreign matter generated from the drive unit inside the processing chamber or foreign matter contained in the outside air is removed from the processing chamber. It is possible to prevent the product from adhering to the product and improve the yield of the product.

[Brief explanation of drawings]

1 and 2 are front sectional views of one embodiment of the heating device applied to the method of the present invention, and FIGS. 3 to 5 are side views of different embodiments of the heating device applied to the present invention, respectively. FIG. 1... Apparatus body, 3... Circulation chamber, 5, 6... Mesh plate, 7... Ventilation room, 8... Processing chamber (bake room), 9... Exhaust chamber, 12... Air supply fan, 13...Exhaust fan, 14...Prefilter, 15...Main filter, 16...Transporting means, 17...Wafer, 18...Loader section, 19
... Unloader section, 22 ... Infrared lamp, 24
... Heater, 25 ... Heater, 26 ... Magnetron.

Claims (1)

[Claims] 1. Applying a liquefied film using a solvent to the surface of a semiconductor wafer, transporting the semiconductor wafer with the applied film into a heat treatment chamber for heating, and cleaning the inside of the heat treatment chamber. A method for heat treatment of a semiconductor wafer, comprising the steps of maintaining the semiconductor wafer in a downflow state of gas, and heating the semiconductor wafer while applying a downflow state of clean gas to the surface of the semiconductor wafer.